Hum. Reprod. Advance Access originally published online on October 12, 2007
Human Reproduction 2008 23(2):458-459; doi:10.1093/humrep/dem321
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Letters to the Editor |
Reply: Ultrasound guided embryo transfer does not offer any benefit in clinical outcome: a randomized controlled study
Centre for Reproductive Medicine, Dutch-Speaking Brussels Free University, Brussels, Belgium
1 Correspondence address. E-mail: kosmasioannis{at}gmail.com
We thank Drs Ata and Urman for their interest in our study (Kosmas et al., 2007
). For the study design, trial committee had to consider two major aspects. Embryo transfer performance is linked with the clinician (Hearns-Stokes et al., 2000), and a certain number of embryo transfers is required for achieving competence equal to experienced providers (Papageorgiou et al., 2001). Therefore, we limited our study to one experienced clinician who performed all embryo transfer.
Decreased uterine contractility during embryo transfer (Fanchin et al., 2001), day of embryo transfer and number of embryos transferred are all factors that play an important role for successful embryo transfers.
Pseudo-randomization methods were the randomization choice in those studies that show a significant positive effect (Buckett, 2003). Pseudo-randomization included randomization based on availability of the ultrasound machine (Prapas et al., 2001), the transfer room (Prapas et al., 2001), ultrasonographer availability (Kan et al., 1999) and randomization done by alternative allocation of patients to each group (Sallam et al., 2002). It is important to understand that pseudo-randomization can introduce significant bias into statistical analysis and this bias can be incorporated in the pooled results. A study that used a true randomization (Garcia-Velasco et al., 2002) did not report significant difference in the outcome after embryo transfer with or without ultrasound guidance. Other studies (Prapas et al., 2001) found no significant difference in pregnancy rates for Day 5 embryo transfers with or without ultrasound guidance.
The corresponding author assumes that embryo transfer with full bladder is a different entity than embryo transfer with empty bladder. A recent meta-analysis of three studies (Abou-Setta, 2007) shows significantly higher likelihood of clinical pregnancy [OR 1.55 (95% CI = 1.16–2.08)] and ongoing pregnancy [OR = 1.44 (95% CI = 1.04–2.04)] with a full bladder. From these three, the two randomized studies included, showed no significant difference in clinical pregnancy rates [OR 1.02 (95% CI = 0.59–1.77)] and only adding the third pseudo-randomized study, makes the difference significant in favor a full bladder embryo transfer. Pooled results incorporate the bias of the single study. Under current evidence, full bladder during embryo transfer is not a different entity from empty bladder, regarding pregnancy rates.
All patients in the ultrasound-guided (US) embryo transfer group had embryo transfer under ultrasound guidance. Sixty patients were excluded because of poor or no visibility during embryo transfer (study flowchart).
Anatomical variability was minimal. In 21 patients, the outer cervical os–uterine fundus distance (as measured, in the US embryo transfer group) was <6 cm. Thirteen of them became pregnant. Most of these measurements were between 5 and 6 cm.
A very neat meta-analysis (Abou-Setta et al., 2007) compared US versus clinical touch method. This meta-analysis states that ultrasound guidance improves clinical pregnancy rates [OR 1.50 (95% CI = 1.34–1.67)]. By excluding the trials (n = 12) with unclear method of randomization or pseudo-randomization, the previous significant difference in clinical pregnancy is lower [OR 1.43 (95% CI = 1.21–1.68)] (Random effects model). Also in this meta-analysis, heterogeneity is significant. The number of patients needed to treat to obtain one additional clinical pregnancy with use of ultrasound guidance need to be calculated. On the basis of these facts, results are debatable.
As a conclusion, all randomized controlled trials have to be uniformly designed, performed by a single clinician and transfer an equal amount of embryos the same day (Day 3 or 5).
References
Abou-Setta AM. Effect of passive uterine straightening during embryo transfer: a systematic review and meta-analysis. Acta Obstet Gynecol Scand (2007) 86:516–522.[CrossRef][Web of Science][Medline]
Abou-Setta AM, Mansour RT, Al-Inany HG, Aboulghar MM, Aboulghar MA, Serour GI. Among women undergoing embryo transfer, is the probability of pregnancy and live birth improved with ultrasound guidance over clinical touch alone? A systemic review and meta-analysis of prospective randomized trials. Fertil Steril (2007) 88:333–341.[CrossRef][Medline]
Buckett WM. A meta-analysis of ultrasound-guided versus clinical touch embryo transfer. Fertil Steril (2003) 80:1037–1041.[CrossRef][Web of Science][Medline]
Fanchin R, Ayoubi JM, Righini C, Olivennes F, Schonauer LM, Frydman R. Uterine contractility decreases at the time of blastocyst transfers. Hum Reprod (2001) 16:1115–1119.
Garcia-Velasco JA, Isaza V, Martinez-Salazar J, Landazabal A, Requena A, Remohi J, Simon C. Transabdominal ultrasound-guided embryo transfer does not increase pregnancy rates in oocyte recipients. Fertil Steril (2002) 78:534–539.[CrossRef][Web of Science][Medline]
Hearns-Stokes RM, Miller BT, Scott L, Creuss D, Chakraborty PK, Segars JH. Pregnancy rates after embryo transfer depend on the provider at embryo transfer. Fertil Steril (2000) 74:80–86.[CrossRef][Web of Science][Medline]
Kan AK, Abdalla HI, Gafar AH, Nappi L, Ogunyemi BO, Thomas A, Ola-ojo OO. Embryo transfer: ultrasound-guided versus clinical touch. Hum Reprod (1999) 14:1259–1261.
Kosmas IP, Janssens R, De Munck L, Al Turki H, Van der Elst J, Tournaye H, Devroey P. Ultrasound-guided embryo transfer does not offer any benefit in clinical outcome: a randomized controlled trial. Hum Reprod (2007) 22:1327–1334.
Papageorgiou TC, Hearns-Stokes RM, Leondires MP, Miller BT, Chakraborty P, Cruess D, Segars J. Training of providers in embryo transfer: what is the minimum number of transfers required for proficiency? Hum Reprod (2001) 16:1415–1419.
Prapas Y, Prapas N, Hatziparasidou A, Vanderzwalmen P, Nijs M, Prapa S, Vlassis G. Ultrasound-guided embryo transfer maximizes the IVF results on day 3 and day 4 embryo transfer but has no impact on day 5. Hum Reprod (2001) 16:1904–1908.
Sallam HN, Agameya AF, Rahman AF, Ezzeldin F, Sallam AN. Ultrasound measurement of the uterocervical angle before embryo transfer: a prospective controlled study. Hum Reprod (2002) 17:1767–1772.
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